Reflective display devices which display an image by controlling the reflection of external light have advantages such as less power consumption as compared to transmissive display devices including a backlight unit.
Some reflective display devices include a surface emission illumination device in the display surface side of the display panel. The illumination device includes, for example, a light source and a lightguide plate which receives light from the light source and transmits the light through a surface opposed to the display panel. With the illumination device, auxiliary light for image display can be produced and the visibility of image can be increased. The illumination device is often referred to as a frontlight.
The illumination device as above transmits the light spreading in the lightguide plate within a suitable range of angles. Thus, the light can be used more efficiently and the visibility of the display device can be improved.